Nematoda Flashcards
Ecdysozoa
Large superphylum that includes:
Nematodes
Tardigrades
Arthropods
Ecdysooa characterized by the presence of
Cuticle
Cuticle
Tough but flexible exoskeleton that protects the organism from external dangers
Ecdysis
Animals regularly molt the cuticle through this
No common body plan
Nematodes are pseudocoelomate, arthropods are coelomate
Nematoda
Free living or parasitic
28,000 identified species; around 16,000 are parasites
Nematodes inhabit
Every habitat
Nematoda characteristics
Psuedocoelomate
Circular cross-section
Most nematodes are tiny
Typically less than 5cm long and many are parasitic
Parasitic nematodes length
Reach more than 1m in length
Nematode cuticle
Made up of collagen
Secreted by the epidermis
Shed throughout growth
Cuticle contains
Hydrostatic pressure in the pseudocel
The cuticle protects
the worm from the external environment
Fluid filled pseudocoel serves as
A hydrostatic skeleton
Hydrostatic pressure
Higher in nematodes than in other animals with hydrostatic skeletons
Nematode muscle
Only have a longitudinal layer
Nematode movement
Whiplike
Nematode muscular movement
Nematodes rely on hydrostatic pressure to antagonize the muscles
Nematodes have a complete digestive system
Mouth, pharynx, intestine, rectum, and anus
Free-living nematodes feed on
bacteria, yeasts, fungi, and algae
Predatory nematodes
Hunt smaller animals such as tardigrades and other nematodes
Adult parasitic nematodes
Have an anaerobic metabolism
Some free-living nematodes and free-living stages of parasitic nematodes
Have an aerobic metabolism
How many longitudinal nerve cords do nematodes have?
4
What do the nerve cords in nematodes fuse to form at the anterior end
Pharyngeal nerve ring around the pharynx
Nematode sensory organs
Simple sensory papillae and more complex amphids
Amphids
Chemosensory organs found near the head
Parastic nematodes’ chemosensory organs
Phasmids
Nematodes do nothave
protonephridia
cillia
Nematode excretory systems either have
Gland cells, a canal system, or both
Most nematodes are Dioecious
Males are smaller than females
Fertilization is internal
Ascaris lumbricoides
One of the most common nematodes involved in human infections
Ascaris lumbricoides transmission
Occurs via contaminated soil or produce contaminated with said soil
Ascaris lumbricoides larvae
Mature in the lungs and then move up to the throat to be swallowed
Adult ascaris lumbricoides
Live in the small intestine
Lifespan ranges from 1 to 2 years
Feed on intestinal contents
Ascaris infection can cause
abdominal symptoms and allergic reactions
Hookworms
Anterior end resembles a hook
Hookworm eggs
Passed through feces and juveniles feed on bacteria
Hookworm infective juveniles
Burrow into human skin and then to the intestine where they feed on blood
Hookworm heavy infections
Cause anemia
Trichinellosis
Caused by a number of species in the genus Trichinella
Trichinella adult females
Produce live young in the smal lintestine
Trichinella juveniles
Penetrate blood vessels
Once the Trichinella juveniles reach skeletal muscle cells
They redirect gene expression
What do muscle cells lose in Trichinella
Striations and becomes a nurse cell that provides nutrition to the worm
Trichinella release into the intestines
Consumption of raw/poorly cooked meat with the cysts
Trichinella infects
Humans, hogs, rats, cats, dogs, and other mammals
Pinworms
Most common nematode parasite in the US
Pinworm scientific name
Enterobius vermicularis
Pinworms cause
Relatively little disease
Pinworm adults live
In the large intestine
Pinworm females lay their eggs
In the anal region at night
Scratching the pinworm itch
Contaminates hands and bedclothes
When pinworm eggs are swallowed
They hatch in the duodenum then mature in the small intestine
Filarial worms
Some species infect humans
Filarial worms (Heartworms)
Frequent causes of disease in dogs
Elephantiasis
Caused by Wuchereria bancrofti and results in parts of the body swelling severly
